Push-button actuated excess current switch

ABSTRACT

This invention relates to a push-button actuated excess current switch which includes a thermal trip, a trip-free release, a switching member connected to the pushbutton and a contact bridge pivotally mounted on the switching member. The contact bridge is in the form of a thin metal plate and is pivoted on the switching member by means of a tubular rivet. The tubular rivet is arranged so that it engages a right-angled portion of one leg of a torsion spring for effecting trip-free release, the other leg of the torsion spring being supported in the housing. The tubular rivet is arranged so that it is displaceably and rotatably guided in a groove in the switching member, which groove extends in the switching direction of the switch.

i I 1 v United States Patent 1 1111 3,708,776 Ellenberger 1451 Jan. 2, 1973 54 PUSH-BUTTON ACTUATED EXCESS 3,551,867 12/1970 lngwersen ..337/66 x CURRENT SWITCH I 1 1 1 5 1 1 Primary Exam'inerRoy N. EnvaLJr. Inventorfi tggrfmgzxlg sy Emhofer was Attorney-Richards 81 Geier [221 Filed: 0ct.22, 1971 57] ABSTRACT 1 APPL 191 7 9 This invention relates to a push-button actuated ex- 1. cess current switch which includesa thermal trip, a r g trip-free release, a switching member connected to the [30] Apphcafio Data pushbutton and a contact bridge pivotally mounted on Oct.26, 1970 Germany ..P 20 52 433.8 the Switching member- The Contact bridge is in the form of a thin metal plate and is pivoted on the 52 U.S. c1 ..337/66 switching member by means of a tubular Five The 51 1111.01. ..H0lh 71/16 110111 73/30 hula five is ammged that it engages a [58] Field of Search 337/62 66 portion of one leg of a torsion spring for effecting tripfree release, the other leg of the torsion spring being 1 v 1 v supported in the housing. The tubular rivet is arranged [56] References Cited so that it is displaceably and rotatably guided in a UNITED STATES PATENTS groove in the switching member, which groove ex- 1 tends in the switching direction of the switch. 2,662,950 12/1953 Christensen ..337/63 X 3,185,793 5/1965 Ellenberger ..337/66 X 11 Claims, 9 Drawing Figures 3 LU 3 3g 13 -1'-]2 Q 'l' 2 l g "'11 -1-\ I NJ! BM :1 23 szn 11 31 z-ZL n w F \25 25 e 1 18 7 V K317 x O y L 5' I I x 6 P'A'TE'N'TED-JAM 2 I975 SHEET 1 OF 3 I Fig.1

ATTOVLNEBS PATENIEDJAN 2 ms SHEET 3 BF 3 lNVE-NTOR: Jcuwb Ezlenber er RYI ATTOILNEfjS v PUSH-BUTTON ACTUATED EXCESS CURRENT SWITCH This invention relates to a push button actuated excess current switch and more especially to such a switch having thermal trip, trip-free release, a switching member connected to a push-button and a contact bridge pivotally mounted on the switchingmember.

An excess current switch of this kind is known (German Patent specification No. 1,134,149 US. Pat. No. 3,185,793) which is of small design, inexpensively and simple to produce with little expenditure on materials and which operates reliably and has a long life. It is possible to construct such a switch with a housing having a depth of 11 mm, a width of 19 mm and a length of 42 mm.

According to the present invention there is provided a push-button actuated excess current switch comprising an elongate housing, a thermal trip which includes a bimetal strip having a retaining member, a trip-free release which includes a torsion spring having first and second legs, the first leg having a right angled'portion and the second leg being supported in the housing, a

switching member associated with the 'pushbutton of the switch, the switching member including a groove extending in the switching direction of the switch and a catch, a contact bridge in the form of a metal plate pivotally mounted on the switching member about an axis which is perpendicular to the longitudinal axis of the housing and being displaceable -in the switching direction under the influence of the spring, the contact bridge including a catch member adapted to engage the catch of the switching member during switching on of the switch whereby the contact bridge is brought into engagement with the retaining member of the bimetal strip, and a perpendicularly projecting tubular rivet arranged in the region of the pivotal axis of the contact bridge, the tubular rivet engaging the right angled portion of the torsion spring and being adapted to be displaceably and rotatably guided in the groove of the switching member.

to 6 mm, the housing being mm wide and 26 mm long. Moreover, dueto the tubular rivet, for pivotable and displaceable mounting of the contact bridge, being guided in a groove of the switching member, an extremely simple production and assembly of the present excess current switch results.

The production may be further simplified by the tubular rivet being designed as a passage in one piece with the contact bridge. As a result of this design securing of the tubular rivet in the contact bridge is omitted. The groove may be provided with a stop for the tubular rivet at its end remote from the push button. In the switched on position the switching member and the push button are retained by this stop.

As in the known excess current switches the housing of the present excess currentswitch may comprise a bowl-shaped housing portion in which the components of the switch are arranged and a plate-like cover. According to a further feature the switching member may be provided with a protruding fillet engaging in a corresponding groove of the bowl-shaped housing portion against the upper boundary wall of which groove the fillet is urged by a disconnection spring when the push button is in the switched off position, the spring on the one hand being supported at the lower end of the switching member and on the other hand in the bowlshaped housing portion. As a result of this construction simple guidance of the switching member together with the push button in the bowl-shaped housing portion is obtained and the push button is maintained in its disconnection position. The push button may have a sloping surface against which the contact bridge is urged by the torsion spring during trip-free release. As a result of this construction the contact bridge is after the trip-free release already in the correct position of disconnection, so that when the push button is released after trip-free release the push button and the contact bridge arrive, under the action of the disconnection spring and without any additional rotation, at the final disconnection position.

For the purpose of forming a counter contact to the fixed contact the contact bridge is provided with a right-angled bend cooperating with a fixed contact member, the free end being bent at a right angle and forming the catch for the driver of the switching bar.

To make the shallow housing depth possible the broad sides of the bimetal strip are arranged'so as to be parallel to the broad sides of the housing and the free end of the bimetal strip is provided with the retaining member which is angularly shaped as contact member and cooperates with a substantially semicircular protuberance of the contact bridge.

As in known excess current switches the present excess current switch may also be provided with at least two connection terminals of lug-shaped design for connection to printed circuits and extending perpendicularly of the cover. These lug-shaped terminals fit accurately into the bores of the grid of the printed circuit. in order to achieve perfect mechanical fastening of the excess current switch to the printed circuit conductor plate-a metal plate is secured to the cover in the vicinity of the push button, which metal plate includes two.

replicas of the lug-shaped terminals whichextend perpendicularly away from the cover and also engage into corresponding bores of the printed conductor plate. The lug-shaped terminals and the upstanding lugs may have shoulders supporting the excess current switch on the conductor plate so as to obtain a definitespacing between the conductor plate and the excesscurrent switch when the lug-like terminals are soldered into the conductor plate.

For the purpose of obtaining a simple fixing for the excess current switch the bowl-shaped housing portion may have indentations at the outer edges of its broad sides into which indentations corresponding resilient projections of a fastening arrangement engage.

The plate-like cover may also have fastening flanges for securing the excess' current switch.

Illustrative embodiments of the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 shows a frontal view of one form of an excess current switch without a cover;

FIG. 2 shows a section along line II--II of FIG. 1;

FIG. 3 shows a section along line III-III of FIG. 1;

FIG. 4 shows the same frontal view as in FIG. 1, the excess current switch being in its switched off condition;

FIG. 5 shows the same frontal view as in FIG. 1, the

excess current switch being in its switched off position with the push button depressed (trip-free release);

FIG. 6 shows a view in perspective of a further form of excess current switch for printed circuits;

FIG. 7 shows a view in perspective of a further excess current switch;

FIG. 8 shows a frontal view of a closed excess current switch; and

FIG. 9 shows a section along the line IXIX of FIG. 8.

The excess current switch illustrated in FIGS. 1 to 5 comprises a housing of insulating material having a bowl-shaped housing portion 1 and a plate-like cover 2. The housing portion 1 and the cover 2 have registering bores 3 into which tubular rivets engage for permanently fixing the cover 2 to the housing portion 1. The bores 3 of the housing portion 1 can be replaced by pins moulded onto the housing portion 1 and engaging into corresponding bores of the cover 2. In this event the cover 2 may be secured to the housing portion 1 by a suitable adhesive. The excess current switch has connection terminals 4, 5 and 6 for the electric connections, which terminals are inserted into corresponding recesses of the housing portion 1 and are maintained in their position bythe cover 2. Additionally the terminal 4 is firmly secured in the housing portion 1 by means of tubular rivet 7.

The terminal 5 has a fixed contact member 8 to which a bent portion 9 of a contact bridge 10 engages when the excess current switch is in the switched on position shown in FIG. 1. The lower end 11 of the portion 9 is bent at a right angle. The contact bridge 10 comprises a flat metal plate having a substantially semicircular protuberance 12 which engages a retaining member 13. The retaining member 13 is in the form of an angled member and its free end is welded to a bimetal strip 14. The bimetal strip 14 has a bent portion 15 by which the bimetal strip is welded to a bimetal carrier 16. The bimetal carrier 16 has a bent portion 17 into which an adjustment screw 18 acting on the bimetal strip 14 is screwed. The intensity of the triggering current of the excess current switch can be accurately adjusted by means of this adjustment screw 18. The terminal 4 and the bimetal carrier-16 are of onepiece construction. The terminal 4 is only used when it is intended to directly heat the bimetal strip 14. The terminal 4 may be omitted when only indirect heating is involved. In this case the terminal 4 is cut off along the severing line 19. For indirect heating the bimetal strip 14 is provided with a heating winding 20 the upper end of which is electrically connected to the bimetal strip 14 and the lower end to the terminal 6, as shown in FIG. 1.

As can be clearly seen from FIG. 2 the contact bridge 10 is provided with a tubular rivet 21 in the region of its pivot axis. A right-angled bent portion 22 of a leg 23 of a torsion spring 24 engages into the tubular rivet 21,

the other leg 25 of the spring 24 being supported on a projection 26 of the housing portion 1.

The tubular rivet 21 engages in a groove 27 of a switching member 28 which is made of insulating material in one piece with a push button 29. Thus, the

' upper end of the fillet 30 engages the upper boundary wall of the groove 31. The lower boundary wall of the groove 27 serves as stop 33, i.e. in the switched on position of FIG. 1 the switching member 28 and the push button 29 engage by means of the stop 33 to the tubular rivet 21 of the contact bridge 10 under the effect of a compression spring .34 one end of which spring is sup-- ported by the lower end of the switching member 28 and the other end is supported at a wall 35 of the housing portion 1. By way of mounting for the compression spring 34 the lower end of the switching member 28 is provided with a frustoconical peg 36. The switching member 28 further has a moulded-on catch 37 capable of cooperating with the bent portion 11 of the contact bridge 10.

For currents of greater intensity the contact point between the retaining nose 13 and the protuberance 12 of the contact bridge 10 may be bridged by stranded copper wire.

The excess current switch described operates as follows:

When in the switched on position as shown in FIG. 1 an excess current occurs, the bimetal strip is heated either directly or indirectly by means of the heating winding 20, so that the bimetal strip deflects in counter-clockwise sense as shown in FIG. 3 and its retaining member moves in the direction of the arrow 38. After the retaining member 13 has moved out of reach of the protuberance 12 of the contact bridge 10 both the torsion spring 24 and the spring 34 become effective unless movement of the push button 29 is arrested. The torsion spring 24 shifts the contact bridge 10 upwardly as shown in FIG. 1. When the contact bridge 10 strikes a projection 39 of the housing portion 1 the contact bridge 10 is pivoted in counterclockwise direction and at the end of its movement it arrives in the position shown in FIG. 4. Concurrently the switching member 28 with the push button 29 also arrive in the disconnection position illustrated in FIG. 4, by virtue of the action of the disconnection spring 34.

When, upon thermal tripping occurring, the push button 29 is held in the depressed position of FIG. 5, release (trip-free release) nevertheless takes place under the action of the torsion spring 24, the contact bridge 10 engaging an oblique surface 40 of the push button 29.

The torsion spring 24 effects not only instantaneous disconnection but also instantaneous connection. When, in the starting position of FIG. 4, the push button 29 is urged into the housing, the catch 37 engages the bent end 11 of the contact bridge 10 and entrains the contact bridge into its connecting position, i.e.

against the action of the torsion spring 24. As soon as the protuberance 12 of the contact bridge engages under the retaining member 13 the push button can be released. Thereby, on the one hand the switching member 28 and the push button 29 are moved upwardly by the action of the disconnection spring 34, and on the other hand the contact bridge 10 is pivoted clockwise about the protuberance 12 as pivot point, by the action of the torsion spring 24. As soon as the bent end 11 of the contact bridge 10 leaves the catch 37 the contact bridge 10 is jerkingly pivoted clockwise by the torsion spring 24 whereby the bent portion 9 of the contact bridge 10, which bend acts as counter-contact, jerkingly comes to adhere to the fixed contact member 8. This abrupt connection is the instantaneous connection mentioned.

The terminals 5, 6 of the excess current switch of FIG. 6 are of lug-shaped design. The pins 5", 6" of the terminals 5', 6' fit into bores of the screen dimensions of a printed circuit. On the cover 2 of this excess current switch a metal plate is additionally riveted which metal plate has two lugs 42 and 43 integral with the plate and also fitting into the screen dimensions of the printed circuit and ensuring torsion-free attaching of this excess current switch. Since the lugs 5", 6", 42, 43 have shoulders 44 which, when the lugs are plugged in, are supported by the conductor plate, a definite spacing between the excess current switch and the conductor plate results.

In the excess current switch of FIG. 7 the cover 2' has two fixing flanges 45 with bores 46 through which fixing screws pass.

In the excess current switch of FIGS. 8 and 9 the housing portion 1' has indentations 47, 48 and 49 into which resilient projections 50 of, for example, plastics fastening means 51 engage when the excess current switch is inserted into the fastening means 51.

I claim:

1. A push-button actuated excess current switch comprising an elongate housing, a thermal trip, said thermal trip including a bimetal strip having a retaining member, a trip-free release, said trip-free release including a torsion spring having first and second legs, the first leg having a right angled portion and the second leg being supported in said housing, a switching member, said switching member being associated with the push-button of the switch, the switching member defining groove means extending in the switching direction of the switch and a catch, a contact bridge, said contact bridge being in the form of a metal plate pivotally mounted on said switching member about an axis which is perpendicular to the longitudinal axis of the housing and being displaceable in the switching direction'under the influence of said torsion spring, the contact bridge including a catch member, said catch member being adapted to engage the catch of the switching member during switching on of the switch whereby the contact bridge is brought into engagement with the retaining member of the bimetal strip, and a perpendicularly projecting tubular rivet, said tubular rivet being arranged in the region of the pivotal axis of the contact bridge, the tubular rivet engaging the right angled portion of the torsion spring and being adapted to be displaceably and rotatably guided in the groove means defined by the switchin member.

2. A switch according to c arm 1 which includes a stop for said tubular rivet, said stop being arranged at the end of the groove means defined by the switching member remote from the push-button.

3. A switch according to claim 1 in which the tubular rivet is integral with the contact bridge and defines passage means therethrough.

4. A switch according to claim 1 in which said housing comprises a bowl-shaped portion and a cover in the form of a plate, the switch components being disposed in the bowl-shaped portion of the housing.

5. A switch according to claim 4 in which the switching member includes a protruding fillet, said fillet extending in the switching direction of the switch and engaging in a corresponding groove means defined by the bowl-shaped portion of the housing against the peripheral wall thereof, a spring, said spring biasing the fillet in the switch-off position of the push-button, the said spring being supported by the switching member and the bowl-shaped portion of the housing.

6. A switch according to claim 4 which includes a fixing arrangement for the switch, the bowl-shaped portion of the housing defining indentation means which are adapted to engage corresponding indentation means of said fixing arrangement.

7. A switch according to claim 4 in which the cover of the housing is provided with fixing flanges.

8. A switch according to claim 1 in which the pushbutton is provided with a sloping surface, said contact bridge being adapted to be urged against said sloping surface by the torsion spring during trip-free release.

9. A switch according to claim 1 which includes a fixed contact member, the contact bridge having a right angled portion, said right angled portion being adapted to co-operate with the fixed contact member, the right angled portion of the contact bridge having afree end portion which is bent to form the catch member of the contact bridge. Y

10. A switch according to claim 1 in which the bimetal strip extends in the longitudinal direction of the housing with the retaining member being formed at a free end thereof and the contact bridge being provided with a semicircular protuberance, said semicircular protuberance being adapted to engage the retaining member of the bimetal strip.

11. A switch according to claim 1 which includes at least two lug-shaped terminals for connection to a printed circuit, said lug-shaped terminals extending perpendicularly away from the plane of the housing and a metal plate, said metal plate having at least two metal lugs in the form of replica terminals extending parallel to the two lug-shaped terminals. 

1. A push-button actuated excess current switch comprising an elongate housing, a thermal trip, said thermal trip including a bimetal strip having a retaining member, a trip-free release, said trip-free release including a torsion spring having first and second legs, the first leg having a right angled portion and the second leg being supported in said housing, a switching member, said switching member being associated with the pushbutton of the switch, the switching member defining groove means extending in the switching direction of the switch and a catch, a contact bridge, said contact bridge being in the form of a metal plate pivotally mounted on said switching member about an axis which is perpendicular to the longitudinal axis of the housing and being displaceable in the switching direction under the influence of said torsion spring, the contact bridge including a catch member, said catch member being adapted to engage the catch of the switching member during switching on of the switch whereby the contact bridge is brought into engagement with the retaining member of the bimetal strip, and a perpendicularly projecting tubular rivet, said tubular rivet being arranged in the region of the pivotal axis of the contact bridge, the tubular rivet engaging the right angled portion of the torsion spring and being adapted to be displaceably and rotatably guided in the groove means defined by the switching member.
 2. A switch according to claim 1 which includes a stop for said tubular rivet, said stop being arranged at the end of the groove means defined by the switching member remote from the push-button.
 3. A switch according to claim 1 in which the tubular rivet is integral with the contact bridge and defines passage means therethrough.
 4. A switch according to claim 1 in which said housing comprises a bowl-shaped portion and a cover in the form of a plate, the switch components being disposed in the bowl-shaped portion of the housing.
 5. A switch according to claim 4 in which the switching member includes a protruding fillet, said fillet extending in the switching direction of the switch and engaging in a corresponding groove means defined by the bowl-shaped portion of the housing against the peripheral wall thereof, a spring, said spring biasing the fillet in the switch-off position of the push-button, the said spring being supported by the switching member and the bowl-shaped portion of the housing.
 6. A switch according to claim 4 which includes a fixing arrangement for the switch, the bowl-shaped portion of the housing defining indentation means which are adapted to engage corresponding indentation means of said fixing arrangement.
 7. A switch according to claim 4 in which the cover of the housing is provided with fixing flanges.
 8. A switch according to claim 1 in which the push-button is provided with a sloping surface, said contact bridge being adapted to be urged against said sloping surface by the torsion spring during trip-free release.
 9. A switch according to claim 1 which includes a fixed contact member, the contact bridge having a right angled portion, said right angled portion being adapted to co-operate with the fixed contact member, the right angled portion of the contact bridge having a free end portion which is bent to form the catch member of the contact bridge.
 10. A switch according to claim 1 in which the bimetal strip extends in the longitudinal direction of the housing with the retaining Member being formed at a free end thereof and the contact bridge being provided with a semicircular protuberance, said semicircular protuberance being adapted to engage the retaining member of the bimetal strip.
 11. A switch according to claim 1 which includes at least two lug-shaped terminals for connection to a printed circuit, said lug-shaped terminals extending perpendicularly away from the plane of the housing and a metal plate, said metal plate having at least two metal lugs in the form of replica terminals extending parallel to the two lug-shaped terminals. 